Objectives: To clinically evaluate the healing of mandibular Miller Class I and II isolated gingival recessions treated with the modified coronally advanced tunnel (MCAT) or laterally closed tunnel (LCT) combined with hyaluronic acid (HA) and subepithelial connective tissue graft (SCTG). Method and materials: Twelve healthy patients exhibiting one isolated mandibular Miller Class I or II (Cairo Class 1) gingival recession of a depth of ≥ 3 mm, were consecutively treated with the MCAT or LCT in conjunction with HA and SCTG. Treatment outcomes were assessed at baseline and at least 6 months postoperatively. The primary outcome variable was complete root coverage (CRC). Results: Postoperative pain and discomfort were low and no complications such as postoperative bleeding, allergic reactions, abscesses, or loss of SCTG occurred. After a mean follow-up of 18.9 ± 10 months, statistically significant (P .0001) root coverage was obtained in all 12 defects. CRC was measured in six out of the 12 cases (50%), four cases showed a root coverage of over 95%, while the remaining two cases reached 80% and 85%. Mean root coverage was 96.09%. Mean keratinized tissue width increased from 1.6 ± 0.8 mm to 4.9 ± 1.3 mm (P .0001) from baseline to follow-up, while mean probing depth showed no statistically significant changes (1.8 ± 0.9 mm vs 1.3 ± 0.5 mm). Conclusion: Within their limits, the present results indicate that the described treatment approach may lead to predictable root coverage of isolated mandibular Miller Class I and II (Cairo Class 1) gingival recessions. (Quintessence Int 2020;51:456–463; doi: 10.3290/j.qi.a44492) Keywords: connective tissue graft, gingival recession, hyaluronic acid, laterally closed tunnel, modified coronally advanced tunnel